It is often necessary to hold a threaded workpiece so that work may be done thereon. The threaded workpiece may be cut off by a power or hand saw. The threaded workpiece may be filed or ground to shape for a particular purpose. The threaded workpiece may be slotted at its free end or have a hole drilled therethrough adjacent its free end for fastening of the threaded workpiece. When such a threaded workpiece is simply clamped in a vice or other similar fixture, the threads thereon may be damaged. Furthermore, since the contact area is very small, it is difficult to hold such a threaded workpiece without slipping. In Duncan U.S. Pat. No. 1,208,552 and Peters U.S. Pat. No. 1,315,238, the attempt was to hold a machine screw or bolt by the clamping of its head. In Billman U.S. Pat. No. 2,438,989 and Totten U.S. Pat. No. 2,827,813, the threaded workpiece is clamped on its threads. In Billman, the clamping holder is divided on a plane passing axially through the threaded openings, and clamping is sideways, at a right angle with respect to that plane. The structure is linear in the sense that all openings have parallel axes. In Totten, clamping is by employment of two threaded plates in line with each other. When the workpiece is threaded into the holes in the two plates, they are clamped together to provide axial clamping of the workpiece. Again, all threaded openings have parallel axes. The structures of Billman and Totten are both difficult to secure in a position where the threaded workpiece can be acted upon.